Apparatus for uniformly coating flat surfaces



APPARATUS FOR UNIFORMLY COATING FLAT SURFACES Original Filed Jan. 13,1932 2 Sheets-Sheet 1 Fig.1.

lnvenTor.

William A.Zwiebel 2 Sheets-Sheet 2 W. A. ZWIEBEL Original Filed Jan. 13,1932 July 7, 1936.

APPARATUS FOR UNIFORMLY COATING FLAT SURFACES lnvenfor. WiHium A.Zwiebe\bygewww kf ATTys- Patented July 7, 1936 'l GEFFIQE APPARATUS FORUNIFORMLY GOATING FLAT SURFACES Application January 13, .1932, SerialNo. 586,279 Renewed November 2.9, 1935 7 Claims.

This invention relates;timprovements in apparatus :for applying a thinuniform coating to a I'flal Surface. The invention broadly statedcomprises .thcvutilization of the surface-tension of .5 the coatingliquid to draw the liquid froma suitable source upon a relatively movingfiat surface.

More specifically the invention relates to improvements in method andapparatus for coating .10 fiat sheets or strips of flexible material,The

invention will be disclosed herein with particular reference to thecoating of flat narrow sheets or strips of celluloid, or the like, witha coating of liquid nitro-cellulose, pyroxylin, or like ma.

1 5 terials, in which the solvent for the coating material also has anaflinity for the material being coated. It will be understood, however,that the process is also adapted to coat any suitable material, such astextiles, paper sheet metal, and

various other fiat materials. V

In performing the method forming the subject matter of thepresentinvention .a narrow capillary column of the liquid coating iscaused to extend upwardly above the normal level of the liquid in thereservoir and the fiat surface to be coated is passed transverselyacross this column and in communication therewith in such manner thatthe surface-tension ofethe liquid not only adheres to the moving surfaceto which it is applied, but by cohesion serves continuously to draw fromthe capillary column of liquid a thin film which progressivelyadheres tothe surface as the movement of the sheet is continued.

Any suitable means may be employed to .pro-

, duce by capillarity an uninterrupted column of a-the liquid coating.This may be accomplished by providing two parallel plates having theiradjacent surfaces in such proximity that capillary action will cause theliquid between .the plates to rise above the normal level of the liquidand in proximity to the. upper edge or edgesoftheplates. If then thesurface to be coated is passedacross the upper ends of said plates at apredetermined rate correlated to the viscosity of the liquid coati g,after a line across the sheet has been moistened by the .liquid, thecontinued movement of the sheet will cause the surface-tension of theliquid continuously to draw a thin film of liquid from the columnproduced by capillary attraction and the progressive adhesion of theliquid to the sheet will form a complete and uniform coating thereupon.By maintaining the liquid level in the reservoir at such height that thecolumn of liquid formed x bycapillary attraction willextend-to-or inproxbeing coated produced by the surface-tension of the liquid chanicalmeans adapted continuously to produce a;. uniformly coated product.Suitable apparatus is illustrated in the accompanying drawings for 1 0coatingasheet of flexible material by the method above described whichis particularly designed for the purpose of coating a narrow sheet orstrip ;of celluloid with a nitro-cellulose or pyroxylin pigmentedcoating of any desired color. 15

In the drawings:

Fig. 1 is a diagrammatic view of an illustrative form of coatingapparatus;

Fig. 2 is an enlarged plan view illustrating a pairof guiding rollersfor supporting a continu- 20 was coated sheet with guiding means forspacing the leads in such manner that the progressive leads may notoverlap, the rollers being spaced apart a sufficient distance to enablecomplete drying of the coated surface while supported by 25 the rollers;

Fig. 3 is an enlarged detail view in side eleva- ;tion of the reservoirfor the liquid coating illustrating the manner in which the liquid isdelivered to the reservoir and also showing in sec- 30 tion the sheetbeing coated;

,Fig l is an enlarged detail plan view of the reservoir shown in Fig. 3,and illustrating in dotted lines thGcDOSltlOIl-Of the sheet which isFig. 5 is a detail view upon a highly magnified scale showing the mannerin which the liquid coating isdrawn upon the sheet from the reservoir bysurface-tension including capillary attraction; and, 40

Fig. 6 is-a detail sideelevation of the. reservoir and means forsupplying the coating liquid thereto with afloat-operated valve forcontrolling the supply lof liquid to .maintain a predetermined liquidlevel in-the reservoir.

edge of which the sheet is passed and in such close proximity theretothat acapillary action is against the end wall.

upon the adjacent surfaces of the wall and plate which will cause acapillary column of coating liquid to extend well above the normal levelof the liquid in the reservoir.

The normal level of the liquid in the reservoir is maintained at suchheight that the capillary column of coating liquid intermediate of theend of the wall and plate will extend to or in proximity to the edge ofthe wall, so that after contact of the under face of the sheet or stripto be coated has been made with the capillary column, and the sheetprogressively drawn over the edge of the plate, the adhesion of theliquid to the sheet or strip will cause the surface-tension of theliquid progressively to draw a thin film of the liquid from thereservoir and cause it to adhere to the sheet, so that if the sheet iscontinuously moved across the edge of the wall and at a uniform rate ofspeed, a thin and uniform coating of the liquid will be applied to thesheet throughout its entire width of contact with the edge of said wall;

Obviously other means may be employed for performing the method hereindescribed. The mechanism particularly illustrated in the accompanyingdrawings comprises a rectangular reservoir I for the coating liquid,supported in any suitable manner, having a flat side wall 2 presenting astraight upper edge 3. A flat plate 4 is located within the reservoir inparallelism with the flatside wall 2 and in such proximity thereto thatthe capillarity of the liquid will cause a narrow column 5 of the liquidto extend well above the normal surface 3 of the liquid in thereservoir.

Means, hereinafter to be described, are provided for maintaining theliquid level 6 in the reservoir at such height that the capillary column5 of the liquid will extend to or in close proximity to the upper edge 3of the wall 2. The under surface of the sheet or strip of material I tobe coated is first caused to contact with the capillary column '5 ofliquid and then is drawn or passed progressively over the edge 3 at a.uniform speed in the manner illustrated in Fig. 5, thereby causing athin film of coating 3 to adhere to the sheet.

As the degree of capillarity of different liquids varies in accordancewith the viscosity of the liquid, means are provided for adjusting theposition of the plate 4 relatively to the wall 2. As illustrated in thedrawings each end of the plate A is provided with a;laterally extendingflange 9 provided with one or more horizontal slots l0 which receives abolt l I mounted in the end wall of the reservoir and provided with anut l2 which when set up will clamp the flange of the sheet By looseningthe nut 12 the plate 4 can be moved toward or from the wall 2 andsecured in such adjusted position that with a proper liquid level in thetank the capillarity of liquid coating of the particular viscosity willextend to or in proximity to the edge 3 of the plate, so that when theunder face of the sheet or strip is brought into contact with thecapillary column of liquid thus formed, the adhesion of the liquid tothe surface of the sheet will, in co-operation with the surface-tensionof the liquid, continuously draw a thin film of the liquid from thereservoir as the sheet is progressively moved across the edge.

In order to permit the liquid to enter the space livered from the nozzlel1 will gradually flow l5, preferably provided with a shut-off valve I610 V and with a downwardly extending nozzle I! having an adjustableneedle valve I8 for accurately controlling the flow of liquid, and sopositioned as to deliverthe liquid upon an inclined preferably V-shapedgutter I9, the lower end of which is sub- 5 merged in and preferablyextends to the bottom of the tank in proximity to the opening in theaperture l3 in the plate 4. By reason of this constructionthe liquiddereservoir has been satisfactorily employed, automatic means may beprovided for insuring the maintenance of the proper constant liquidlevel in the tank. A suitable automatic device of this 35 character, isillustrated in Fig. 6"in which the nozzle I1 is provided with a valve 20having an upwardly extending valve stem 2lprovioled at its upper endwith a cylindrical offset 22 which engages a slot 23 inthe end of alever 24 which is, go

fulcrumed upon a pintle- 25 at the upper end of a bracket 26 extendinglaterally from the body of the nozzle I1, the'opposite endof the nozzle7 r 7 having a slot 21'which is-engaged by the offset upper end 28 of arod 29, the lower end of which gio is connected to a float 3!! partiallyimmersed in the liquid in the reservoir. The rod 29 may be guided in anysuitable manner as by a bracket 3| extending laterallyfrom the nozzle I1and a bracket 32 mounted upon the inclined, trough org ao gutter l9.Obviously variations in the liquid level in the tank will raise or lowerthe float 30 and thereby close or open the valve2il in such a manner asso to control the amount of liquid delivered from the tank l5 as tomaintain a constant predetermined liquid level in the reservoir at alltimes. V

Any suitable means may be provided for causing the sheet or strip ofmaterial to be coated to pass over the edge 3 of the wall 4 of thereseril voir at a constant rate of speed and in close contact therewiththroughout the width of the sheet or strip. In the preferredconstruction illustrated herein, which is adapted to coat a strip ofcelluloid, or othersuitable material, and endless- 6 feeding belt 33 isutilized. The belt 33 is mounted upon rollers 34 and 35, one of which,preferably the roller 35, is driven at a uniform speed. The belt 33 isarranged at a suitable angle to the horizontal and is so positioned asto press the strip 1 firmly against the upper edge 3 of the wall 2throughout the entire width of the strip. Preferably the belt 33 is ofconsiderably less width than the strip and does not contact with theedge 1 f rthe 'wall thereby avoiding 'the accumulation .of any 20f theliquid :coating upon the :belt and consequent 11f the belt. 1

"fIhessheet =.or strip 1 :is drawn from :a :roll 36 over .22. :guide:roll .31 which presses :against the lupp'erlead :of the endless belt133 in advance of themoll 34, so that the strip is maintained in properfrictional :contact with the belt 33 asit i passes around the :rolls 3Aand the i-rolls 35 and throughout the length :of the 'lower lead of thebelt betweensaid rolls. Desirablya cleaner 35.1: is positioned to engagethe face .of the sheet'or "strip to be coatedand remove therefrom anydust or "foreign matter which may have accumulated upon'the strip.

suitable'means may :be provided for dryin'gthe coating upon the stripafter it is delivere'd from the r011 35. As illustrated herein the strip-'I', after leaving the belt- 33 at a tangent to the roll 35, 'is ledover a roll 38, thence over'a roll 39 'looatedat a considerable distancefrom the rolliaB. The rolls 38 and 39 may be of any desired length andthe strip guided progressively over thes'e rollsas illustrated inFig. 2.Any suitable means may bra-provided for guiding the strip so that itwill not contact or overlap as it passes progressively over the rolls 38and 39. A convenient means, which is illustrated in Figs. 1 and 2,comprises bars 48 located at suitable distances from the lines ofcontact of the strip with its respective rolls and provided with pins 4|so positioned as to engage the edges of the strip as it progressivelyapproaches the respective rolls and thereby so to direct the strip uponthe rolls as to prevent contact of adjacent portions of the strip.

The rolls may be placed such distances apart and the strip carriedaround the rolls a sufficient number of times to permit complete dryingof the coating. The dried coated strip 1 may then be led to and woundupon a suitable winding or storage roll 42. The winding roll 42 and therolls 38 and 39 may be driven in any suitable manner to maintain theproper tension upon the strip 1 as will be readily understood by thoseskilled in the art.

The apparatus disclosed herein is one which has been employed in thecoating of strips of flexible material, such as celluloid, with apigmented pyroxylin or cellulose coating, but obviously may be and hasbeen employed for coating other sheets or strips of flexible materialincluding fabric, flexible steel strips, and the like. Obviously, themethod may be employed to coat any fiat surface with a suitable liquidadherent to the surface and of such viscosity that the surface-tensionof the liquid will insure continuous delivery of the liquid from thereservoir to the surface of a sheet moved at a substantially uniformspeed across the straight edge of the wall of the reservoir incommunication with a capillary column of liquid of the character abovedescribed.

It will be understood that the particular mech- I iflat plate .locatedwithin said reservoir in parallelismwith said flat wall .and iinzsuchproximity thereto as to produce by capillarity a column of :liquidtherebetween, means for maintaining the liquid in the reservoir at suchlevel that said :capillary :column will extend approximately to .theupper edge of the flat wall of the reservoir, means for moving the.surface of the sheet in contact with said edge and thence incommunication with said liquid column only, whereby a thin uniform filmof said liquid will be drawn from saidreservoir upon said surface by thesurface tensionof the liquid, and means for adjusting the flat platerelatively to said flat wall in correlation to variations in thecapillary characteristics of different liquids.

'2. Apparatus for coating a sheet of flexible material with liquidcomprising a reservoir having a 'flatwall presenting a straight edge, aflat plate located'within said reservoir in parallelism withsaid fiatwall and in such proximity thereto as to produce by capillarity a columnof liquid therebetween, means for maintaining the liquid in thereservoir at such level that said capillary column will extendapproximately to the upper edge of the fiat wall of the reservoir, andmeans for continuously moving the lower surface of said sheet across theupper edge of said flat wall in an upwardly inclined plane and thence incommunication with said liquid column only, whereby a thin uniform filmof said liquid will be drawn from said reservoir upon said surface bythe surface tension of the liquid.

3. Apparatus for coating a sheet of flexible material with liquidcomprising a reservoir having a fiat wall presenting a straight edge, aflat plate located within said reservoir in parallelism with said flatwall and in such proximity thereto as to produce by capillarity a columnof liquid therebetween, means for maintaining the liquid in thereservoir at such level that said capillary column will extendapproximately to the upper edge of the flat wall of the reservoir, andmeans for feeding the sheet of flexible material comprising an upwardlyinclined flexible endless belt of narrower width than the width of saidsheet positioned to maintain the lower surface of the sheet in uniformcontact with the straight edge of said flat wall and thence incommunication with the capillary column of said liquid.

4. Apparatus for coating a narrow sheet of flexible material with liquidcomprising a reservoir having a. fiat wall presenting a straight edge, afiat plate located within said reservoir in parallelism with said fiatwall and in such proximity thereto as to produce by capillarity a columnof liquid therebetween, means for feeding said narrow sheet comprisingan inclined endless belt having its lower lead engaging the upper flatedge of said reservoir, means for guiding the narrow sheet in frictionalengagement with said endless belt, whereby said endless belt willmaintain the surface of the sheet in close contact with the upper edgeof the reservoir and thence in communication with the capillary columnof said liquid, and means for supporting the traveling coated sheet asufiicient time to permit the drying of the coating thereof.

5. Apparatus for coating 2. narrow sheet of flexible material withliquid comprising a reservoir having a flat wall presenting a straightedge, a fiat plate located within said reservoir in parallelism withsaid flat wall and in such proximity thereto as to produce bycapillarity a column of liquid therebetween, means for feeding saidnarrow sheet comprising an inclined endless belt having its lowerleadengaging the upper fiat edge 7 of said reservoir; means for guiding thenarrow v sheet in frictional engagement with said endless them, andguiding means for preventing: overlapping of successive leads of thesheets around said rollers. V V

6. Apparatus for coating a flat surface of material with liquid whichcomprises a reservoir for-liquid, means for producing from the liquid bycapillary attraction a narrow straight column of said liquid, means formoving the surface to be coated transversely across and in continuouscommunication with said column, and means. for feeding liquid to saidreservoir including an inclined gutter extending into the liquid of.said

reservoir, and means for delivering 'liquid'upon said gutter at asufiicientl'rateto maintain the liquid level inthe' reservoir at suchheight that the capillary column of liquid wi1l:extend=into s proximityto the edge ofsaidiflat wall and in communication with the surface ofsaid 'materiaL' 7. Apparatus for coating a flat, surface of materialwithliquid which comprises areservoir for liquid, means for producingfrom'the liquid by capillary attraction a narrow straight column ofvsaid liquid, means for moving the'surface to becoated transverselyacross'and in continuous communication with said column, means forfeeding liquid to said reservoir including aninclined gutter extendinginto the liquid of said reservoir,.,-a

source of supply of liquid, a conduit leading from said source to saidgutter, a valve in said conduit and a float carried by the liquid of.said reservoir connected to said valve operable to cause such actuationof the valve as to maintain such liquid 20 level in the reservoir atsuch heightthat the capillary column of liquid will extend intoproximity to, the edge of said flat wall and in cornmunica tion with thesurface of said materiah j WILLIAM AozwIEBfilL, v 25

